Channel estimation enhancements

ABSTRACT

The disclosure relates in some aspects to techniques for improved channel estimation. For example, a device can specify a pilot structure where pilot density differs over time. As another example, a device can indicate that a pilot from a prior transmission time interval (TTI) can be used for channel estimation. As another example, a device can employ frequency domain physical resource block (PRB) bundling with the bundling information signaling. As yet another example, a device can use an adjustable traffic-to-pilot ratio (TPR) for throughput optimization. Other aspects, embodiments, and features are also discussed and claimed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of provisionalpatent application No. 62/073,683 filed in the U.S. patent office onOct. 31, 2014, the entire content of which is incorporated herein byreference.

INTRODUCTION

Aspects of the disclosure relate generally to wireless communication,and more specifically, but not exclusively, to techniques for enhancingchannel estimation that can be useful to provide better channel qualityestimates and/or reduced latency associated with decoding based onchannel estimates.

Wireless communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources.

In some wireless communication networks, a wireless device decodesand/or demodulates received data based on an estimate of the channelthrough which the data traveled. Some wireless communication networksemploy pilot-assisted channel estimation where a base station (e.g., anenhanced Node B (eNB)) broadcasts pilot signals and an access terminal(e.g., a mobile device such as a user equipment (UE)) that receives thepilot signals generates an estimate of the channel based on the pilotsignals. For example, in 3rd Generation Partnership Project (3GPP) LongTerm Evolution (LTE), an eNB broadcasts a pilot reference signal such asa demodulation reference signal (DMRS), whereby a UE that receives thepilot reference signal generates a channel estimate based on thereceived pilot reference signal.

Conventionally (e.g., in LTE), DMRS pilots are fixed both in time andfrequency. Also, in LTE, DMRS pilots are transmitted at the end of eachslot. Thus, one set of pilots could be estimated only at the end of agiven transmission time interval (TTI).

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a simplified summary of some aspects of thedisclosure to provide a basic understanding of such aspects. Thissummary is not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present variousconcepts of some aspects of the disclosure in a simplified form as aprelude to the more detailed description that is presented later.

In one aspect, the disclosure provides an apparatus configured forcommunication. The apparatus includes a processing circuit configured todetermine a pilot structure where pilot density differs over time withina transmission period; and a communication interface coupled to theprocessing circuit and configured to transmit an indication of the pilotstructure.

Another aspect of the disclosure provides a method of communicationincluding determining a pilot structure where pilot density differs overtime within a transmission period; and transmitting an indication of thepilot structure.

Another aspect of the disclosure provides an apparatus configured forcommunication. The apparatus including means for determining a pilotstructure where pilot density differs over time within a transmissionperiod; and means for transmitting an indication of the pilot structure.

Another aspect of the disclosure provides a non-transitorycomputer-readable medium storing computer-executable code, includingcode to determine a pilot structure where pilot density differs overtime within a transmission period; and transmit an indication of thepilot structure.

These and other aspects of the disclosure will become more fullyunderstood upon a review of the detailed description, which follows.Other aspects, features, and implementations of the disclosure willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific implementations of the disclosurein conjunction with the accompanying figures. While features of thedisclosure may be discussed relative to certain implementations andfigures below, all implementations of the disclosure can include one ormore of the advantageous features discussed herein. In other words,while one or more implementations may be discussed as having certainadvantageous features, one or more of such features may also be used inaccordance with the various implementations of the disclosure discussedherein. In similar fashion, while certain implementations may bediscussed below as device, system, or method implementations it shouldbe understood that such implementations can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of an access networkin which one or more aspects of the disclosure may find application.

FIG. 2 is a block diagram illustrating an example of an access terminalin communication with an access point in a communication systemaccording to some aspects of the disclosure.

FIG. 3 is a block diagram illustrating an example of a communicationsystem where a base station (BS) signals a pilot structure to a UE inaccordance with some aspects of the disclosure.

FIG. 4 illustrates an example of a pilot structure in accordance withsome aspects of the disclosure.

FIG. 5 is a block diagram illustrating another example of acommunication system where a base station (BS) signals an indication ofTTI filtering to a UE in accordance with some aspects of the disclosure.

FIG. 6 is a block diagram illustrating another example of acommunication system where a base station (BS) signals an indication ofphysical resource block (PRB) bundling to a UE in accordance with someaspects of the disclosure.

FIG. 7 is a block diagram illustrating another example of acommunication system where a base station (BS) an indication of atraffic-to-pilot ratio (TPR) to a UE in accordance with some aspects ofthe disclosure.

FIG. 8 is a block diagram illustrating an example hardwareimplementation for an apparatus (e.g., an electronic device) that canexecute one or more of the methods for supporting communication inaccordance with some aspects of the disclosure.

FIG. 9 is a flowchart illustrating an example of a process forcommunication in accordance with some aspects of the disclosure.

FIG. 10 is a flowchart illustrating an example of a process involvingdetermining a pilot structure in accordance with some aspects of thedisclosure.

FIG. 11 is a block diagram illustrating an example hardwareimplementation for another apparatus (e.g., an electronic device) thatcan execute one or more of the methods for supporting communication inaccordance with some aspects of the disclosure.

FIG. 12 is a flowchart illustrating an example of a process forcommunication in accordance with some aspects of the disclosure.

FIG. 13 is a block diagram illustrating an example hardwareimplementation for another apparatus (e.g., an electronic device) thatcan execute one or more of the methods for supporting communication inaccordance with some aspects of the disclosure.

FIG. 14 is a flowchart illustrating an example of a process involvingtransmission of a pilot indication in accordance with some aspects ofthe disclosure.

FIG. 15 is a flowchart illustrating an example of a process involvingtransmission of an indication of a pilot structure in accordance withsome aspects of the disclosure.

FIG. 16 is a flowchart illustrating an example of a process involvingtransmission of an indication of a traffic-to-pilot ratio (TPR) inaccordance with some aspects of the disclosure.

FIG. 17 is a block diagram illustrating an example hardwareimplementation for another apparatus (e.g., an electronic device) thatcan execute one or more of the methods for supporting communication inaccordance with some aspects of the disclosure.

FIG. 18 is a flowchart illustrating an example of a process involvinggeneration of a channel estimate in accordance with some aspects of thedisclosure.

FIG. 19 is a flowchart illustrating another example of a processinvolving generation of a channel estimate in accordance with someaspects of the disclosure.

FIG. 20 is a flowchart illustrating an example of a process involvingselection of a transmit power in accordance with some aspects of thedisclosure.

FIG. 21 illustrates an example of a wireless communication networkwithin which aspects of the disclosure may be implemented.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

The disclosure relates in some aspects to improvements in channelestimation. For example, a first device may adapt its pilots and/orprovide information to enhance channel estimation at a second device. Asa more specific example, an access point (e.g., a base station such asan eNB) may adapt its pilots and/or provide information to enhancechannel estimation at an access terminal. Through the use of thedisclosed techniques, better channel quality estimates may be achievedand/or latency associated with decoding based on channel estimates canbe reduced.

The disclosure relates in some aspects to a pilot structure that has avariable pilot density. For example, pilot density can be denser (e.g.,denser in at least one of time, frequency, or power) at the beginning ofa data burst that at a later portion of the data burst. As anon-limiting example, a first TTI of a data burst could include fourpilots while subsequent TTIs of the data burst include two pilots.Accordingly, a device can obtain information for a channel estimateearlier as compared to conventional techniques. Also, a device may useperiodic pilot updates to improve the channel estimate.

The disclosure relates in some aspects to across-TTI filteringtechniques. For example, a device can apply pilot filtering acrosssubframes (SFs). As a more specific example, a device can useinformation that it previously obtained for a prior TTI or frame tofilter a current TTI or frame.

In some aspects, these two techniques facilitate demodulation on-the-flyat a device (e.g., an access terminal). Consequently, in some cases,improvements may be seen in demodulation latency, decoding latency, andmemory requirements.

The disclosure relates in some aspects to enhanced frequency domainphysical resource block (PRB) bundling. For example, a device canspecify a uniform pilot structure with PRB bundling to facilitatechannel estimation. In addition, network (NW) signaling of a precodingmatrix indicator (PMI) can enable joint channel estimation acrossmultiple PRBs and/or PRB bundle groups.

The disclosure relates in some aspects to providing an adjustabletraffic-to-pilot ratio (TPR) for throughput optimization. For example,devices may use different TPRs for different modulation and codingschemes (MCSs), ranks, and so forth.

The various concepts presented throughout this disclosure may beimplemented across a broad variety of communication systems, networkarchitectures, and communication standards. Referring to FIG. 1, by wayof example and without limitation, an example access network 100 isshown. The access network 100 can be implemented according to variousnetwork technologies including, without limitation, fifth generation(5G) technology, fourth generation (4G) technology, third generation(3G) technology, and other network architectures. Thus, various aspectsof the disclosure may be extended to networks based on Long TermEvolution (LTE), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes),Universal Mobile Telecommunications System (UMTS), Global System forMobile Communications (GSM), Code Division Multiple Access (CDMA),Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB),Bluetooth, and/or other suitable systems. The actual telecommunicationstandard, network architecture, and/or communication standard employedwill depend on the specific application and the overall designconstraints imposed on the system.

The access network 100 includes multiple cellular regions (cells),including cells 102, 104, and 106, each of which may include one or moresectors. Cells may be defined geographically, e.g., by coverage area. Ina cell that is divided into sectors, the multiple sectors within a cellcan be formed by groups of antennas with each antenna responsible forcommunication with ATs in a portion of the cell. For example, in thecell 102, antenna groups 112, 114, and 116 may each correspond to adifferent sector. In the cell 104, antenna groups 118, 120, and 122 mayeach correspond to a different sector. In the cell 106, antenna groups124, 126, and 128 may each correspond to a different sector.

The cells 102, 104, and 106 may include several access terminals (ATs)that may be in communication with one or more sectors of each cell 102,104, or 106. For example, ATs 130 and 132 may be in communication withan access point (AP) 142, ATs 134 and 136 may be in communication withan AP 144, and ATs 138 and 140 may be in communication with an AP 146.In various implementations, an AP may be referred to or implemented as abase station, a NodeB, an eNodeB, and so on; while an AT may be referredto or implemented as a user equipment (UE), a mobile station, a remotewireless device, and so on.

FIG. 2 is a block diagram of system 200 including an access point (AP)210 in communication with an access terminal (AT) 250, where the AP 210and the AT 250 may be configured to provide functionality as taughtherein. The AP 210 may be the AP 142, 144, or 146 in FIG. 1, and the AT250 may be the AT 130, 132, 134, 136, 138, or 140 in FIG. 1. In variousoperating scenarios, the AP 210 and/or the AT 250 may be a transmitteror transmitting device, or a receiver or receiving device, or both.Examples of such transmitters, transmitting devices, receivers, andreceiving devices are illustrated in FIGS. 1, 3, 5-8, 11, 13, 17, and21.

In a downlink communication from the AP 210 to the AT 250, a controlleror processor (controller/processor) 240 may receive data from a datasource 212. Channel estimates may be used by the controller/processor240 to determine the coding, modulation, spreading, and/or scramblingschemes for the transmit processor 220. These channel estimates may bederived from a reference signal transmitted by the AT 250 or fromfeedback from the AT 250. A transmitter 232 may provide various signalconditioning functions including amplifying, filtering, and modulatingframes onto a carrier for downlink transmission over a wireless mediumthrough antennas 234A-234N. The antennas 234A-234N may include one ormore antennas, for example, including beam steering bidirectionaladaptive antenna arrays, MIMO arrays, or any other suitabletransmission/reception technologies.

At the AT 250, a receiver 254 receives the downlink transmission throughantennas 252A-252N (e.g., representing one or more antennas) andprocesses the transmission to recover the information modulated onto thecarrier. The information recovered by the receiver 254 is provided to acontroller/processor 290. The controller/processor 290 descrambles anddespreads the symbols, and determines the most likely signalconstellation points transmitted by the AP 210 based on the modulationscheme. These soft decisions may be based on channel estimates computedby the controller/processor 290. The soft decisions are then decoded anddeinterleaved to recover the data, control, and reference signals. TheCRC codes are then checked to determine whether the frames weresuccessfully decoded. The data carried by the successfully decodedframes will then be provided to a data sink 272, which representsapplications running in the AT 250 and/or various user interfaces (e.g.,display). Control signals carried by successfully decoded frames will beprovided to a controller/processor 290. When frames are unsuccessfullydecoded, the controller/processor 290 may also use an acknowledgement(ACK) and/or negative acknowledgement (NACK) protocol to supportretransmission requests for those frames.

In the uplink from the AT 250 to the AP 210, data from a data source 278and control signals from the controller/processor 290 are provided. Thedata source 278 may represent applications running in the AT 250 andvarious user interfaces (e.g., keyboard). Similar to the functionalitydescribed in connection with the downlink transmission by the AP 210,the controller/processor 290 provides various signal processingfunctions including CRC codes, coding and interleaving to facilitateFEC, mapping to signal constellations, spreading with OVSFs, andscrambling to produce a series of symbols. Channel estimates, derived bythe controller/processor 290 from a reference signal transmitted by theAP 210 or from feedback contained in a midamble transmitted by the AP210, may be used to select the appropriate coding, modulation,spreading, and/or scrambling schemes. The symbols produced by thecontroller/processor 290 will be utilized to create a frame structure.The controller/processor 290 creates this frame structure bymultiplexing the symbols with additional information, resulting in aseries of frames. The frames are then provided to a transmitter 256,which provides various signal conditioning functions includingamplification, filtering, and modulating the frames onto a carrier foruplink transmission over the wireless medium through the antennas252A-252N.

The uplink transmission is processed at the AP 210 in a manner similarto that described in connection with the receiver function at the AT250. A receiver 235 receives the uplink transmission through theantennas 234A-234N and processes the transmission to recover theinformation modulated onto the carrier. The information recovered by thereceiver 235 is provided to the controller/processor 240, which parseseach frame. The controller/processor 240 performs the inverse of theprocessing performed by the controller/processor 290 in the AT 250. Thedata and control signals carried by the successfully decoded frames maythen be provided to a data sink 239. If some of the frames wereunsuccessfully decoded by the receive processor, thecontroller/processor 240 may also use a positive acknowledgement (ACK)and/or negative acknowledgement (NACK) protocol to supportretransmission requests for those frames.

The controller/processors 240 and 290 may be used to direct theoperation at the AP 210 and the AT 250, respectively. For example, thecontroller/processors 240 and 290 may provide various functionsincluding timing, peripheral interfaces, voltage regulation, powermanagement, and other control functions. The computer readable media ofmemories 242 and 292 may store data and software for the AP 210 and theAT 250, respectively.

In accordance with various aspects of the disclosure, an element, or anyportion of an element, or any combination of elements may be implementedwith controller/processors 240 and 290 (e.g., that may each include oneor more processors). The controller/processors 240 and 290 areresponsible for general processing, including the execution of softwarestored in the memory 252 or 292. The software, when executed by thecontroller/processors 240 and 290, causes the controller/processors 240and 290 to perform the various functions described below for anyparticular apparatus. The memory 252 or 292 may also be used for storingdata that is manipulated by the controller/processors 240 and 290 whenexecuting software.

In various aspects of the disclosure, an apparatus may be utilized in awireless communication network, as a scheduling entity (e.g., the AP210) and/or as a non-scheduling or subordinate entity (e.g., the AT250). Also, in various aspects of the disclosure, an apparatus mayemploy peer-to-peer (P2P) wireless communication. For example, two ormore P2P devices may cooperate to form a mesh wireless communicationnetwork. In any case, the apparatus may communicate with one or morewireless entities over an air interface. In any wireless communicationnetwork, channel conditions corresponding to the air interface willchange over time.

Many networks accordingly use one or more rate control loops todynamically adapt to the channel. For example, a transmitting device mayconfigure one or more transmission parameters, including but not limitedto a modulation and coding scheme (MCS), a transmission power, etc., totarget a desired error rate at the receiving device. The receivingdevice that is receiving a packet-switched data stream typically checksthe integrity of packets (e.g., using a cyclic redundancy check or CRC,a checksum, PHY layer channel coding pass/fail status, etc.) and mayreport back to the transmitting device using an acknowledgment ornon-acknowledgment. This integrity check and reporting frequently,though not always, takes the form of an automatic repeat request (ARQ)and/or hybrid automatic repeat request (HARQ) algorithm. In otherexamples, any suitable algorithm or means of providing feedbackinformation or response transmissions from the receiving device to thetransmitting device may be used, such as reports relating to channelquality.

In some network designs, DMRS pilots have a fixed pattern in both timeand frequency. This fixed pattern may lead to performance loss in thebase station and the per-subframe channel estimate. In addition, theremay be demodulation latency due to this fixed pilot structure.

The disclosure relates in some aspects to techniques for improvedchannel estimation. In a first example technique, a device (e.g., a basestation) can specify a pilot structure where pilot density differs overtime. For example, a device can adapt DMRS pilot density over time tofacilitate earlier pilot processing and thereby improve the decodingtimeline for channel estimation. This technique may thus be referred tocolloquially as a “pilot bootstrap” technique. In a second exampletechnique, a device can indicate that a pilot from a prior transmissiontime interval (TTI) can be used for channel estimation. Accordingly,devices may employ DMRS across-TTI bundling to improve channelestimation quality without significantly affecting the associatedsignaling overhead and/or processing overhead. In a third exampletechnique, a device can employ frequency domain physical resource block(PRB) bundling. In a fourth example technique, a device can use anadjustable traffic-to-pilot ratio (TPR) for throughput optimization.

In some aspects, these techniques can facilitate extrapolation anddecision-directed/iterative channel estimation at a device (e.g., anaccess terminal) that receives pilots, thereby improving decodingperformance and reducing decoding latency. Accordingly, through the useof decision-directed and iterative channel estimations based on theteachings herein, such a device can improve its channel estimationaccuracy and latency as compared to conventional schemes.

Each of the above four techniques will be described in turn withreference to FIGS. 3-7. For purposes of illustration, these figures mayillustrate various components in the context of channel estimation forDMRS pilot systems and/or LTE technology. It should be appreciated,however, that the teachings herein may employ other types of devices andbe implemented using other types of radio technologies andarchitectures. Also, various operations may be described as beingperformed by specific types of components (e.g., eNBs, base stations,client devices, peer-to-peer devices, UEs, and so on). It should beunderstood, however, that these operations can be performed by othertypes of devices. To reduce the complexity of these figures, only a fewexample components are shown. It should be appreciated, however, thatthe teachings herein can be implemented using a different number ofcomponents or other types of components.

Pilot Structure

The disclosure relates in some aspects to a pilot structure where thedensity of pilots may vary over time.

FIG. 3 illustrates a communication system 300 where a base station (BS)304 (e.g., an eNB) communicates pilot structure information and otherinformation to a UE 302 in accordance with the teachings herein. In thecommunication system 300, the UE 302 is served by the base station 304.In some aspects, the UE 302 may correspond to the AT 250 of FIG. 2, orany of the ATs 130, 132, 134, 136, 138, or 140 of FIG. 1. In someaspects, the base station 304 may correspond to the AP 210 of FIG. 2, orany of the APs 142, 144, or 146 of FIG. 1. The UE 302 and the basestation 304 include respective transmitters 306 and 308 and receivers310 and 312 for supporting communicating via a downlink (DL) 314 and anuplink (UL) 316 as indicated. That is, the UE 302 transmits UL signaling318 to the base station 304 and the base station transmits DL signaling320 to the UE 302.

As mentioned above, it should be noted that the discussions of aspectsof the technology discussed in this disclosure relative to base stationsand UEs are for purposes of explanation. In other scenarios, thedisclosed base stations and UEs could instead be other types ofcomponents/devices capable of wireless communication. For example, theteachings here may be applied among a wireless user device and awireless network device, among multiple wireless user devices, or amongmultiple wireless network devices.

A pilot structure 400 of FIG. 4 shown symbols in the time domain(x-axis) and the frequency domain (y-axis). A transmission period 402includes multiple TTIs (e.g., a first TTI 404). In some aspects, thetransmission period 402 may correspond to a data burst. Also, whilethree TTIs are shown in FIG. 1 for purposes of illustration, atransmission period could include a different number of TTIs.

Pilot symbols 406 (represented by shaded boxes) are defined at thebeginning of each TTI. In some aspects, this facilitates early detectionof the pilot symbols in each TTI.

In addition, extra pilot symbols 408 (represented by shaded boxes) areprovided in the first TTI at symbols 4 and 5. Extra pilot symbols couldbe provided at other symbols in other implementations (e.g., in additionto or other than the pilot symbols at symbols 4 and 5). The use of extrasymbols can increase the pilot density (e.g., at the beginning of a databurst). For example, upon a cold start or a beamforming (BF) change, abase station can signal a UE to schedule denser pilots, therebybootstrapping the UE's channel estimation. The UE receives the pilotsearlier and can therefore generate a channel estimate sooner. Inaddition, the UE can receive more pilot information earlier andtherefore generate a more accurate estimate earlier. The UE getsnotified of extra pilot symbols in this case via indicator bits in thecontrol channel payload. Accordingly, the UE's channel estimationprocess is assisted (colloquially referred to as bootstrapping) byproviding the UE with earlier pilots, etc.

Pilot density can be increased in terms of at least one of time,frequency, or transmit power. For example, more pilots can be sent insome TTIs than other TTIs. As another example, additional pilots (e.g.,early pilots) can be transmitted on additional frequency bands (e.g.,concurrently or at different times). As yet another example, thetransmit power can be higher for some pilots (e.g., earlier pilots) thanothers.

Referring again to FIG. 3, based on one or more criterion, a processingcircuit 322 of the base station 304 generates a pilot structure andtransmits an indication of the pilot structure 326 to the UE 302. Thebase station 304 may also transmit an indication of whether prior TTIscan be used for decoding, PMIs for PRB bundling, and TPR indications asdiscussed below. At some point in time, the base station 304 alsotransmits pilots to the UE 302 according to the pilot structure.

A processing circuit 324 of the UE 302 uses a received pilot structure(derived from the received pilot structure indication and pilots 328) toreceive pilots from the base station 304. The processing circuit 324also generates a channel estimate 330 based on received pilots (from thereceived pilot structure indication and pilots 328) and decodes (e.g.,demodulates) received data based on the channel estimate. The UE 302also may send the channel estimate 330 or parameters derived from thechannel estimate to the base station 304 to enable the base station 304to adapt communication parameters based on a received channel estimate332.

As discussed herein, through the use of the dynamic pilot structure astaught herein, the UE 302 may advantageously generate more accuratechannel estimates and mitigate associated delays. For example, byreceiving pilots front-loaded into a transmission period, the UE 302 cangenerate a channel estimate more quickly and/or more accurately. Also,by receiving pilots prior to the end of a TTI, the UE 302 can generate achannel estimate on-the-fly (e.g., as compared to LTE where the pilot isat the end of the TTI). Furthermore, periodic pilot updates can bereceived and used to improve the channel estimation.

TTI Pilot Filtering

The disclosure relates in some aspects to using a pilot from a previousTTI for channel estimation. For example, a base station can signal a UEto utilize pilots in the previous TTI to improve channel estimationquality and the decoding timeline. This technique can be used, forexample, in cases where the TTI has not changed (e.g., in cases wherebeamforming has not changed between TTIs).

FIG. 5 illustrates a communication system 500 where a base station (BS)504 communicates pilot information and other information as taughtherein to a UE 502 in accordance with the teachings herein. In thecommunication system 500, the UE 502 is served by the base station 504.In some aspects, the UE 502 may correspond to the AT 250 of FIG. 2, orany of the ATs 130, 132, 134, 136, 138, or 140 of FIG. 1. In someaspects, the base station 504 may correspond to the AP 210 of FIG. 2, orany of the APs 142, 144, or 146 of FIG. 1. The UE 502 and the basestation 504 include respective transmitters 506 and 508 and receivers510 and 512 for supporting communicating via a downlink (DL) 514 and anuplink (UL) 516 as indicated. That is, the UE 502 transmits UL signaling518 to the base station 504 and the base station transmits DL signaling520 to the UE 502.

A processing circuit 522 of the base station 504 generates a TTIfiltering indication 526 that indicates whether pilots from prior TTIscan be used for channel estimation for the current TTI. The base station504 transmits this indication to the UE 502. In addition, at some pointin time, the base station 504 transmits pilots to the UE 502 accordingto the current pilot structure.

A processing circuit 524 of the UE 502 receives the TTI filteringindication and pilots 528 and generates a channel estimate 530 based onthe received pilots and the indicated filtering technique indicated.Thus, in some cases, the processing circuit 524 generates the channelestimate 530 based on pilots from a current TTI and pilots from earlierTTIs. In some aspects, the processing circuit 524 may decode (e.g.,demodulate) received data based on the channel estimate. The UE 502 alsosends the channel estimate to the base station 504 to enable theprocessing circuit 522 of the base station 504 to adapt communicationparameters based on a received channel estimate 532.

Through the use of the dynamic pilot techniques taught herein, the UE502 may advantageously generate more accurate channel estimates andmitigate associated delays. For example, by receiving pilots from priorTTIs, the accuracy of the channel estimation or the channel estimationtime may be improved.

PRB Bundling

The disclosure relates in some aspects to enhanced frequency domainpilot bundling. In some aspects, this involves PRB bundling. Uniformpilot spacing can be employed in a bundled PRB region to enable betterchannel estimation. Wider-band bundling can be employed to tradeoffchannel estimation performance for sub-band (SB) scheduling flexibilityand/or beamforming (BF) gain.

Wideband bundling in the presence of precoding change can be employed toimprove channel estimation quality. For example, a base station cantransmit signals to indicate a precoding matrix indicator (PMI) changeacross PRB bundles to enable joint wideband (WB) channel estimationacross multiple PRB bundles. In some implementations, a base stationsignals the difference between neighbor resource block (RB) PMIs. Insome implementations, a base station performs wideband beamforming basedon a sounding reference signal (SRS) and sub-band fine tuning based onchannel state feedback (CSF). UE-PMI can also be used to adjust precoderdifferences across PRBs. For example, UE reported sub-band PMI can beguaranteed to be applied N subframes later.

FIG. 6 illustrates a communication system 600 where a base station (BS)604 communicates pilot information and other information as taughtherein to a UE 602 in accordance with the teachings herein. In thecommunication system 600, the UE 602 is served by the base station 604.In some aspects, the UE 602 may correspond to the AT 250 of FIG. 2, orany of the ATs 130, 132, 134, 136, 138, or 140 of FIG. 1. In someaspects, the base station 604 may correspond to the AP 210 of FIG. 2, orany of the APs 142, 144, or 146 of FIG. 1. The UE 602 and the basestation 604 include respective transmitters 606 and 608 and receivers610 and 612 for supporting communicating via a downlink (DL) 614 and anuplink (UL) 616 as indicated. That is, the UE 602 transmits UL signaling618 to the base station 604 and the base station transmits DL signaling620 to the UE 602.

A processing circuit 622 of the base station 604 generates a PRBbundling indication 626 (e.g., a PMI applied across different PRBs) thatindicates, for example, how PRBs may be bundled. The base station 604transmits this indication to the UE 602. In addition, at some point intime, the base station 604 transmits pilots to the UE 602 according tothe current pilot structure.

A processing circuit 624 of the UE 602 receives the PRB bundlingindication and pilots 628 and generates a channel estimate 630 based onthe received pilots and the indicated PRB bundling scheme. Theprocessing circuit 624 may also decode (e.g., demodulate) received databased on the channel estimate. The UE 602 sends the channel estimate (orparameters derived from the channel estimate) to the base station 604 toenable the processing circuit 622 of the base station 604 to adaptcommunication parameters based on a received channel estimate 632.

Through the use of the dynamic pilot techniques taught herein, the UE602 may advantageously generate more accurate channel estimates andmitigate associated delays. For example, by receiving pilots that areuniform across a PRB bundle, the UE 602 can generate a more accuratechannel estimate (e.g., for a wideband channel).

TPR Adjustment

The disclosure relates in some aspects to power optimization for a DMRSpilot. In some aspects, flexible traffic-to-pilot ratio (TPR) adjustmentcan be employed to optimize DMRS traffic performance. For example, DMRSpower can be optimized for different MCSs, ranks, rates, and so on. Tothis end, a first device (e.g., a base station) may signal a TPR toneighbor devices (e.g., UEs) for joint demodulation.

FIG. 7 illustrates a communication system 700 where a base station (BS)704 communicates pilot information and other information as taughtherein to a UE 702 in accordance with the teachings herein. In thecommunication system 700, the UE 702 is served by the base station 704.In some aspects, the UE 702 may correspond to the AT 250 of FIG. 2, orany of the ATs 130, 132, 134, 136, 138, or 140 of FIG. 1. In someaspects, the base station 704 may correspond to the AP 210 of FIG. 2, orany of the APs 142, 144, or 146 of FIG. 1. The UE 702 and the basestation 704 include respective transmitters 706 and 708 and receivers710 and 712 for supporting communicating via a downlink (DL) 714 and anuplink (UL) 716 as indicated. That is, the UE 702 transmits UL signaling718 to the base station 704 and the base station transmits DL signaling720 to the UE 702.

At some point in time, a processing circuit 722 of the base station 704sends a TPR indication 726 to the UE 702 (e.g., by sending anappropriate signal to the UE via the downlink signaling 720). Aprocessing circuit 724 of the UE 702 generates control signals 730 tocontrol the transmit power of the transmitter 706 based on received TPRindications (from the received TPR indication and pilots 728).

The processing circuit 724 also generates a channel estimate (not shown)based on received pilots (from the received TPR indications and pilots728). The transmitter 706 transmits this channel estimate (or parametersderived from the channel estimate) to the receiver 712 via the uplink716. Accordingly, the processing circuit 722 of the base station 704 canadjust communication parameters based on a received channel estimate732.

As discussed herein, through the use of the TPR indications, the UE 702may advantageously generate more accurate channel estimates and mitigateassociated delays. For example, the UE 702 can dynamically set itstransmit power accordingly to TPR information received from the basestation 704. Thus different TPRs may be used for different transmissionschemes (e.g., for different MCSs, different ranks, etc.).

The functionality disclosed in two or more of FIG. 3, 5, 6, or 7 may becombined in some implementations. For example, a base station couldinclude the functionality of two or more of the base station 304, thebase station 504, the base station 604, or the base station 704. Asanother example, a UE could include the functionality of two or more ofthe UE 302, the UE 502, the UE 602, or the UE 702.

Example Apparatus

FIG. 8 illustrates a block diagram of an example hardware implementationof an apparatus 800 configured to communicate according to one or moreaspects of the disclosure. For example, the apparatus 800 could embodyor be implemented within a base station (e.g., an eNB), a UE, or someother type of device that supports wireless communication. In variousimplementations, the apparatus 800 could embody or be implemented withinan access terminal, an access point, or some other type of device. Invarious implementations, the apparatus 800 could embody or beimplemented within a mobile phone, a smart phone, a tablet, a portablecomputer, a server, a personal computer, a sensor, an entertainmentdevice, a vehicular component, medical devices, or any other electronicdevice having circuitry.

The apparatus 800 includes a communication interface (e.g., at least onetransceiver) 802, a storage medium 804, a user interface 806, a memorydevice (e.g., a memory circuit) 808, and a processing circuit (e.g., atleast one processor) 810. In various implementations, the user interface806 may include one or more of: a keypad, a display, a speaker, amicrophone, a touchscreen display, of some other circuitry for receivingan input from or sending an output to a user.

These components can be coupled to and/or placed in electricalcommunication with one another via a signaling bus or other suitablecomponent, represented generally by the connection lines in FIG. 8. Thesignaling bus may include any number of interconnecting buses andbridges depending on the specific application of the processing circuit810 and the overall design constraints. The signaling bus links togethervarious circuits such that each of the communication interface 802, thestorage medium 804, the user interface 806, and the memory device 808are coupled to and/or in electrical communication with the processingcircuit 810. The signaling bus may also link various other circuits (notshown) such as timing sources, peripherals, voltage regulators, andpower management circuits, which are well known in the art, andtherefore, will not be described any further.

The communication interface 802 provides a means for communicating withother apparatuses over a transmission medium. In some implementations,the communication interface 802 includes circuitry and/or programmingadapted to facilitate the communication of information bi-directionallywith respect to one or more communication devices in a network. In someimplementations, the communication interface 802 is adapted tofacilitate wireless communication of the apparatus 800. In theseimplementations, the communication interface 802 may be coupled to oneor more antennas 812 as shown in FIG. 8 for wireless communicationwithin a wireless communication system. The communication interface 802can be configured with one or more standalone receivers and/ortransmitters, as well as one or more transceivers. In the illustratedexample, the communication interface 802 includes a transmitter 814 anda receiver 816. The communication interface 802 serves as one example ofa means for receiving and/or means transmitting.

The memory device 808 may represent one or more memory devices. Asindicated, the memory device 808 may maintain pilot-related information818 along with other information used by the apparatus 800. In someimplementations, the memory device 808 and the storage medium 804 areimplemented as a common memory component. The memory device 808 may alsobe used for storing data that is manipulated by the processing circuit810 or some other component of the apparatus 800.

The storage medium 804 may represent one or more computer-readable,machine-readable, and/or processor-readable devices for storingprogramming, such as processor executable code or instructions (e.g.,software, firmware), electronic data, databases, or other digitalinformation. The storage medium 804 may also be used for storing datathat is manipulated by the processing circuit 810 when executingprogramming. The storage medium 804 may be any available media that canbe accessed by a general purpose or special purpose processor, includingportable or fixed storage devices, optical storage devices, and variousother mediums capable of storing, containing or carrying programming.

By way of example and not limitation, the storage medium 804 may includea magnetic storage device (e.g., hard disk, floppy disk, magneticstrip), an optical disk (e.g., a compact disc (CD) or a digitalversatile disc (DVD)), a smart card, a flash memory device (e.g., acard, a stick, or a key drive), a random access memory (RAM), a readonly memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM),an electrically erasable PROM (EEPROM), a register, a removable disk,and any other suitable medium for storing software and/or instructionsthat may be accessed and read by a computer. The storage medium 804 maybe embodied in an article of manufacture (e.g., a computer programproduct). By way of example, a computer program product may include acomputer-readable medium in packaging materials. In view of the above,in some implementations, the storage medium 804 may be a non-transitory(e.g., tangible) storage medium.

The storage medium 804 may be coupled to the processing circuit 810 suchthat the processing circuit 810 can read information from, and writeinformation to, the storage medium 804. That is, the storage medium 804can be coupled to the processing circuit 810 so that the storage medium804 is at least accessible by the processing circuit 810, includingexamples where at least one storage medium is integral to the processingcircuit 810 and/or examples where at least one storage medium isseparate from the processing circuit 810 (e.g., resident in theapparatus 800, external to the apparatus 800, distributed acrossmultiple entities, etc.).

Programming stored by the storage medium 804, when executed by theprocessing circuit 810, causes the processing circuit 810 to perform oneor more of the various functions and/or process operations describedherein. For example, the storage medium 804 may include operationsconfigured for regulating operations at one or more hardware blocks ofthe processing circuit 810, as well as to utilize the communicationinterface 802 for wireless communication utilizing their respectivecommunication protocols.

The processing circuit 810 is generally adapted for processing,including the execution of such programming stored on the storage medium804. As used herein, the terms “code” or “programming” shall beconstrued broadly to include without limitation instructions,instruction sets, data, code, code segments, program code, programs,programming, subprograms, software modules, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

The processing circuit 810 is arranged to obtain, process and/or senddata, control data access and storage, issue commands, and control otherdesired operations. The processing circuit 810 may include circuitryconfigured to implement desired programming provided by appropriatemedia in at least one example. For example, the processing circuit 810may be implemented as one or more processors, one or more controllers,and/or other structure configured to execute executable programming.Examples of the processing circuit 810 may include a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic component, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor mayinclude a microprocessor, as well as any conventional processor,controller, microcontroller, or state machine. The processing circuit810 may also be implemented as a combination of computing components,such as a combination of a DSP and a microprocessor, a number ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, an ASIC and a microprocessor, or any other number of varyingconfigurations. These examples of the processing circuit 810 are forillustration and other suitable configurations within the scope of thedisclosure are also contemplated.

According to one or more aspects of the disclosure, the processingcircuit 810 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 810may be configured to perform any of the steps, functions, and/orprocesses described with respect to FIGS. 1-7 and 9-10. As used herein,the term “adapted” in relation to the processing circuit 810 may referto the processing circuit 810 being one or more of configured, employed,implemented, and/or programmed to perform a particular process,function, operation and/or routine according to various featuresdescribed herein.

The processing circuit 810 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out any one of the operationsdescribed in conjunction with FIGS. 1-7 and 9-10. The processing circuit810 serves as one example of a means for transmitting and/or a means forreceiving. In some implementations, the processing circuit 810incorporates the functionality of the processing circuit 322 of FIG. 3.

According to at least one example of the apparatus 800, the processingcircuit 810 may include one or more of a circuit/module for determininga pilot structure 820, a circuit/module for transmitting 822, or acircuit/module for changing a beamforming configuration 824. In someimplementations, the circuit/module for determining a pilot structure820, the circuit/module for transmitting 822, and the circuit/module forchanging a beamforming configuration 824 correspond, at least in part,to the processing circuit 322 of FIG. 3.

The circuit/module for determining a pilot structure 820 may includecircuitry and/or programming (e.g., code for determining a pilotstructure 826 stored on the storage medium 804) adapted to performseveral functions relating to, for example, determining a pilotstructure where pilot density differs over time within a transmissionperiod. In some implementations, the circuit/module for determining apilot structure 820 defines the pilot structure. For example, thecircuit/module for determining a pilot structure 820 may define a pilotstructure where the pilot density is higher at a beginning of thetransmission period (e.g., the pilot density at a beginning portion ofthe transmission period is higher than the pilot density at a laterportion of the transmission period). As another example, thecircuit/module for determining a pilot structure 820 may define a pilotstructure where the pilot density is different for differenttransmission time intervals (TTIs) within the transmission period. Insome aspects, the pilot density further differs with respect tofrequency during the transmission period and/or with respect to transmitpower during the transmission period. In some implementations, thecircuit/module for determining a pilot structure 820 obtains the pilotstructure. For example, the circuit/module for determining a pilotstructure 820 may obtain pilot structure information from a component ofthe apparatus (e.g., the memory device 808, the receiver 816, or someother component) or directly from a device (e.g., a base station, a userdevice, etc.) that broadcasts this information. The circuit/module fordetermining a pilot structure 820 outputs the determined pilot structureinformation (e.g., stores the information in the memory device 808 orsends the information to another component of the apparatus 800). Insome implementations, the communication interface 802 includes thecircuit/module for determining a pilot structure 820 and/or the code fordetermining a pilot structure 826.

The circuit/module for transmitting 822 may include circuitry and/orprogramming (e.g., code for transmitting 828 stored on the storagemedium 804) adapted to perform several functions relating to, forexample, transmitting an indication or other information. In someimplementations, the circuit/module for transmitting 822 is configuredto transmit an indication of pilot structure. Initially, thecircuit/module for transmitting 822 obtains data to be transmitted. Forexample, the circuit/module for transmitting 822 may obtain this datafrom a component of the apparatus (e.g., the memory device 808, thecircuit/module for determining a pilot structure 820, or some othercomponent). In some implementations, the circuit/module for transmitting822 processes (e.g., encodes) the data to be transmitted. Thecircuit/module for transmitting 822 then causes the data to betransmitted. For example, the circuit/module for transmitting 822 canpass the data to the transmitter 814 for subsequent radio frequency (RF)transmission. In some implementations, the transmitter 814 includes thecircuit/module for transmitting 822 and/or the code for transmitting828.

The circuit/module for changing a beamforming configuration 824 mayinclude circuitry and/or programming (e.g., code for changing abeamforming configuration 830 stored on the storage medium 804) adaptedto perform several functions relating to, for example, changing abeamforming configuration used by the communication interface 802.Initially, the circuit/module for changing a beamforming configuration824 receives an indication that a beamforming configuration is to bechanged. In addition, the circuit/module for changing a beamformingconfiguration 824 obtains parameters (e.g., from the memory device 808,the communication interface 802, or some other component) for the newbeamforming configuration. These parameters may include, for example, anamplitude value and a phase value for each antenna subject toconfiguration. The circuit/module for changing a beamformingconfiguration 824 then generates, based on the obtained parameters, atleast one control signal that controls at least one component (e.g., anamplifier and/or a phase shifter) of the transmitter 814 and/or thereceiver 816 to provide the desired beamforming when the transmitter 814transmits radio frequency (RF) signals and/or the receiver 816 receivesRF signals.

As mentioned above, programming stored by the storage medium 804, whenexecuted by the processing circuit 810, causes the processing circuit810 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 810, may cause the processing circuit 810 toperform the various functions, steps, and/or processes described hereinwith respect to FIGS. 1-7 and 9-10 in various implementations. As shownin FIG. 8, the storage medium 804 may include one or more of the codefor determining a pilot structure 826, the code for transmitting 828, orthe code for changing a beamforming configuration 830.

Example Processes

FIG. 9 illustrates a process 900 for communication in accordance withsome aspects of the disclosure. The process 900 may take place within aprocessing circuit (e.g., the processing circuit 810 of FIG. 8), whichmay be located in a base station, an access terminal, or some othersuitable apparatus (device). In some implementations, the process 900represents operations performed by the processing circuit 322 of FIG. 3.Of course, in various aspects within the scope of the disclosure, theprocess 900 may be implemented by any suitable apparatus capable ofsupporting communication-related operations.

At block 902, an apparatus (e.g., a base station) determines a pilotstructure where pilot density differs over time within a transmissionperiod. Thus, such a pilot structure could be used for advanced channelestimation (pilot bootstrapping) as discussed herein.

In some aspects, the transmission period may correspond to a trafficburst. In some aspects, the pilot structure may be for a demodulationreference signal (DMRS).

In some aspects, the pilot density relates to at least one of: time,frequency, or transmit power. For example, in some aspects, the pilotdensity may differ with respect to transmit power during thetransmission period. As another example, in some aspects, the pilotdensity may differ with respect to frequency during the transmissionperiod.

In some aspects, pilots in the pilot structure may be located at abeginning portion and/or a middle portion of a transmission timeinterval (TTI). In some aspects, the pilot density may be higher at abeginning of the transmission period (e.g., the pilot density at abeginning portion of the transmission period is higher than the pilotdensity at a later portion of the transmission period). In some aspects,the pilot density may be different for different transmission timeintervals (TTIs) within the transmission period.

In some implementations, the circuit/module for determining a pilotstructure 820 of FIG. 8 performs the operations of block 902. In someimplementations, the code for determining a pilot structure 826 of FIG.8 is executed to perform the operations of block 902.

At block 904, the apparatus transmits an indication of the pilotstructure. For example, upon establishing communication (or changingbeamforming) with a UE, an eNB may transmit this indication (e.g., bybroadcasting the indication or by unicasting the indication to a UE).Thus, in some aspects, the process 900 may involve changing abeamforming configuration, wherein the pilot structure is defined as aresult of the change in (the changing of) the beamforming configuration.

In some implementations, the circuit/module for transmitting 822 of FIG.8 performs the operations of block 904. In some implementations, thecode for transmitting 828 of FIG. 8 is executed to perform theoperations of block 904.

FIG. 10 illustrates a process 1000 for communication in accordance withsome aspects of the disclosure. In some aspects, the process 1000 may beimplemented in conjunction with the process 900 of FIG. 9. For example,the process 1000 may be, at least in part, a trigger for block 902. Theprocess 1000 may take place within a processing circuit (e.g., theprocessing circuit 810 of FIG. 8), which may be located in a basestation, an access terminal, or some other suitable apparatus (device).In some implementations, the process 1000 represents operationsperformed by the processing circuit 322 of FIG. 3. Of course, in variousaspects within the scope of the disclosure, the process 1000 may beimplemented by any suitable apparatus capable of supportingcommunication operations.

At block 1002, an apparatus (e.g., a base station) changes a beamformingconfiguration. For example, this change may be due to a change inchannel conditions, movement of the apparatus and/or an associatedapparatus, an obstruction, or some other condition.

In some implementations, the circuit/module for changing a beamformingconfiguration 824 of FIG. 8 performs the operations of block 1002. Insome implementations, the code for changing a beamforming configuration830 of FIG. 8 is executed to perform the operations of block 1002.

At block 1004, the apparatus defines a pilot structure (e.g., as inblock 902 above) as a result of the change in (the changing of) thebeamforming structure at block 1002. For example, a specific pilotstructure may be indicated for a certain beamforming configuration in anattempt to provide the best communication quality possible.

In some implementations, the circuit/module for determining a pilotstructure 820 of FIG. 8 performs the operations of block 1004. In someimplementations, the code for determining a pilot structure 826 of FIG.8 is executed to perform the operations of block 1004.

Example Apparatus

FIG. 11 illustrates a block diagram of an example hardwareimplementation of another apparatus 1100 configured to communicateaccording to one or more aspects of the disclosure. For example, theapparatus 1100 could embody or be implemented within a UE, a basestation (e.g., an eNB), or some other type of device that supportswireless communication. In various implementations, the apparatus 1100could embody or be implemented within an access terminal, an accesspoint, or some other type of device. In various implementations, theapparatus 1100 could embody or be implemented within a mobile phone, asmart phone, a tablet, a portable computer, a server, a personalcomputer, a sensor, an entertainment device, a vehicular component,medical devices, or any other electronic device having circuitry.

The apparatus 1100 includes a communication interface (e.g., at leastone transceiver) 1102, a storage medium 1104, a user interface 1106, amemory device 1108 (e.g., storing pilot-related information 1118), and aprocessing circuit (e.g., at least one processor) 1110. In variousimplementations, the user interface 1106 may include one or more of: akeypad, a display, a speaker, a microphone, a touchscreen display, ofsome other circuitry for receiving an input from or sending an output toa user. The communication interface 1102 may be coupled to one or moreantennas 1112, and may include a transmitter 1114 and a receiver 1116.In general, the components of FIG. 11 may be similar to correspondingcomponents of the apparatus 800 of FIG. 8.

According to one or more aspects of the disclosure, the processingcircuit 1110 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 1110may be configured to perform any of the steps, functions, and/orprocesses described with respect to FIGS. 1-7 and 12. As used herein,the term “adapted” in relation to the processing circuit 1110 may referto the processing circuit 1110 being one or more of configured,employed, implemented, and/or programmed to perform a particularprocess, function, operation and/or routine according to variousfeatures described herein.

The processing circuit 1110 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out any one of the operationsdescribed in conjunction with FIGS. 1-7 and 12. The processing circuit1110 serves as one example of a means for transmitting and/or a meansfor receiving. In some implementations, the processing circuit 1110incorporates the functionality of the processing circuit 324 of FIG. 3.

According to at least one example of the apparatus 1100, the processingcircuit 1110 may include one or more of a circuit/module for receiving1120, a circuit/module for generating a channel estimate 1122, or acircuit/module for decoding 1124. In some implementations, thecircuit/module for receiving 1120, the circuit/module for generating achannel estimate 1122, and the circuit/module for decoding 1124correspond, at least in part, to the processing circuit 324 of FIG. 3.

The circuit/module for receiving 1120 may include circuitry and/orprogramming (e.g., code for receiving 1126 stored on the storage medium1104) adapted to perform several functions relating to, for example,receiving information. In some implementations, the circuit/module forreceiving 1120 is configured to receive an indication of a pilotstructure. In some implementations, the circuit/module for receiving1120 is configured to receive a pilot according to an indicated pilotstructure. Initially, the circuit/module for receiving 1120 obtainsinformation. For example, the circuit/module for receiving 1120 mayobtain this information from a component of the apparatus (e.g., thereceiver 1116, the memory device 1108, or some other component) ordirectly from a device (e.g., a base station, a user device, etc.) thattransmitted the information. In some implementations, the circuit/modulefor receiving 1120 identifies a location in the memory device 1108 orsome other component and invokes a read of that location to receive theinformation. In some implementations, the circuit/module for receiving1120 processes (e.g., decodes) the received information. Thecircuit/module for receiving 1120 then outputs the received information(e.g., stores the information in the memory device 1108 or sends theinformation to another component of the apparatus 1100). In someimplementations, the receiver 1116 includes the circuit/module forreceiving 1120 and/or the code for receiving 1126.

The circuit/module for generating a channel estimate 1122 may includecircuitry and/or programming (e.g., code for generating a channelestimate 1128 stored on the storage medium 1104) adapted to performseveral functions relating to, for example, generating a channelestimate based on received information (e.g., a received pilot).Initially, the circuit/module for generating a channel estimate 1122obtains the received information. For example, the circuit/module forgenerating a channel estimate 1122 may obtain this information from acomponent of the apparatus (e.g., the memory device 1108, the receiver1116, the circuit/module for receiving 1120, or some other component) ordirectly from a device (e.g., a base station, a user device, etc.) thattransmits this information. The circuit/module for generating a channelestimate 1122 then estimates the channel over which the information wasreceived based on information known about the originally transmittedinformation as well as transmitter and receiver parameters. Finally, thecircuit/module for generating a channel estimate 1122 outputs thechannel estimate to a component of the apparatus 1100 (e.g., the memorydevice 1108, the circuit/module for decoding 1124, or some othercomponent). In some implementations, the communication interface 1102includes the circuit/module for generating a channel estimate 1122and/or the code for generating a channel estimate 1128.

The circuit/module for decoding 1124 may include circuitry and/orprogramming (e.g., code for decoding 1130 stored on the storage medium1104) adapted to decode data from a TTI prior to the end of the TTI.Initially, the circuit/module for decoding 1124 obtains receivedinformation. For example, the circuit/module for decoding 1124 mayobtain this information from a component of the apparatus 1100 (e.g.,the memory device 1108, the receiver 1116, the circuit/module forreceiving 1120, or some other component) or directly from a device(e.g., a base station, a user device, etc.) that transmitted theinformation. In some implementations, the circuit/module for decoding1124 identifies a memory location of a value in the memory device 1108and invokes a read of that location. In any event, the circuit/modulefor decoding 1124 commences the processing of the information receivedfor a given TTI prior to the end of the TTI. For example, thecircuit/module for decoding 1124 may process a pilot that is received ator near a beginning or a middle section of the TTI without waiting forthe entirety of the TTI to be received. The circuit/module for decoding1124 then outputs the decoded information to a component of theapparatus 1100 (e.g., the memory device 1108 or some other component).In some implementations, the receiver 1116 includes the circuit/modulefor decoding 1124 and/or the code for decoding 1130.

As mentioned above, programming stored by the storage medium 1104, whenexecuted by the processing circuit 1110, causes the processing circuit1110 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 1110, may cause the processing circuit 1110 toperform the various functions, steps, and/or processes described hereinwith respect to FIGS. 1-7 and 12 in various implementations. As shown inFIG. 11, the storage medium 1104 may include one or more of the code forreceiving 1126, the code for generating a channel estimate 1128, or thecode for decoding 1130.

Example Process

FIG. 12 illustrates a process 1200 for communication in accordance withsome aspects of the disclosure. In some aspects, the process 1200 may becomplementary to the process 900 of FIG. 9. The process 1200 may takeplace within a processing circuit (e.g., the processing circuit 1110 ofFIG. 11), which may be located in a base station, an access terminal, orsome other suitable apparatus. In some implementations, the process 1200represents operations performed by the processing circuit 324 of FIG. 3.Of course, in various aspects within the scope of the disclosure, theprocess 1200 may be implemented by any suitable apparatus capable ofsupporting communication operations.

At block 1202, an apparatus (e.g., a UE) receives an indication of apilot structure where pilot density differs over time within atransmission period. For example, a UE can receive an indicationtransmitted by an eNB (e.g., as discussed above in conjunction withblock 904 of FIG. 9).

In some aspects, the pilot density relates to at least one of: time,frequency, or transmit power. In some aspects, the pilot density ishigher at a beginning portion of the transmission period (e.g., thepilot density at a beginning of the transmission period is higher thanthe pilot density at a later portion of the transmission period).

In some implementations, the circuit/module for receiving 1120 of FIG.11 performs the operations of block 1202. In some implementations, thecode for receiving 1126 of FIG. 11 is executed to perform the operationsof block 1202.

At block 1204, the apparatus receives a pilot according to the indicatedpilot structure. For example, a UE can receive a pilot that wastransmitted at a time and/or frequency specified by the indicated pilotstructure. In some aspects, the pilot may be a demodulation referencesignal (DMRS). In some aspects, pilots in the pilot structure arelocated at a beginning portion and/or a middle portion of a transmissiontime interval (TTI).

In some implementations, the circuit/module for receiving 1120 of FIG.11 performs the operations of block 1204. In some implementations, thecode for receiving 1126 of FIG. 11 is executed to perform the operationsof block 1204.

At block 1206, the apparatus generates a channel estimate based on thereceived pilot. In some aspects, the apparatus generates the channelestimate based on a pilot received prior to an end of the TTI.

In some implementations, the circuit/module for generating a channelestimate 1122 of FIG. 11 performs the operations of block 1206. In someimplementations, the code for generating a channel estimate 1128 of FIG.11 is executed to perform the operations of block 1206.

At optional block 1208, the apparatus may decode data from the TTI priorto the end of the TTI. In some aspects, this decoding may be based onthe channel estimate generated at block 1206.

In some implementations, the circuit/module for decoding 1124 of FIG. 11performs the operations of block 1208. In some implementations, the codefor decoding 1130 of FIG. 11 is executed to perform the operations ofblock 1208.

Example Apparatus

FIG. 13 illustrates a block diagram of an example hardwareimplementation of another apparatus 1300 configured to communicateaccording to one or more aspects of the disclosure. For example, theapparatus 1300 could embody or be implemented within a base station(e.g., an eNB), a UE, or some other type of device that supportswireless communication. In various implementations, the apparatus 1300could embody or be implemented within an access terminal, an accesspoint, or some other type of device. In various implementations, theapparatus 1300 could embody or be implemented within a mobile phone, asmart phone, a tablet, a portable computer, a server, a personalcomputer, a sensor, an entertainment device, a vehicular component,medical devices, or any other electronic device having circuitry.

The apparatus 1300 includes a communication interface (e.g., at leastone transceiver) 1302, a storage medium 1304, a user interface 1306, amemory device 1308 (e.g., storing pilot-related information 1318), and aprocessing circuit (e.g., at least one processor) 1310. In variousimplementations, the user interface 1306 may include one or more of: akeypad, a display, a speaker, a microphone, a touchscreen display, ofsome other circuitry for receiving an input from or sending an output toa user. The communication interface 1302 may be coupled to one or moreantennas 1312, and may include a transmitter 1314 and a receiver 1316.In general, the components of FIG. 13 may be similar to correspondingcomponents of the apparatus 800 of FIG. 8.

According to one or more aspects of the disclosure, the processingcircuit 1310 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 1310may be configured to perform any of the steps, functions, and/orprocesses described with respect to FIGS. 1-7 and 14-16. As used herein,the term “adapted” in relation to the processing circuit 1310 may referto the processing circuit 1310 being one or more of configured,employed, implemented, and/or programmed to perform a particularprocess, function, operation and/or routine according to variousfeatures described herein.

The processing circuit 1310 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out any one of the operationsdescribed in conjunction with FIGS. 1-7 and 14-16. The processingcircuit 1310 serves as one example of a means for transmitting and/or ameans for receiving. In various implementations, the processing circuit1310 may incorporate the functionality of the processing circuit 522 ofFIG. 5, the processing circuit 622 of FIG. 6, or the processing circuit722 of FIG. 7.

According to at least one example of the apparatus 1300, the processingcircuit 1310 may include one or more of a circuit/module for determiningthat a pilot structure is specified for successive TTIs 1320, acircuit/module for transmitting 1322, a circuit/module for identifying aPRB bundle 1324, a circuit/module for selecting a pilot structure 1326,or a circuit/module for determining a TPR 1328. In variousimplementations, the circuit/module for determining that a pilotstructure is specified for successive TTIs 1320, the circuit/module fortransmitting 1322, the circuit/module for identifying a PRB bundle 1324,the circuit/module for selecting a pilot structure 1326, and thecircuit/module for determining a TPR 1328 may correspond, at least inpart, to the processing circuit 522 of FIG. 5, the processing circuit622 of FIG. 6, or the processing circuit 722 of FIG. 7.

The circuit/module for determining that a pilot structure is specifiedfor successive TTIs 1320 may include circuitry and/or programming (e.g.,code for determining that a pilot structure is specified for successiveTTIs 1330 stored on the storage medium 1304) adapted to perform severalfunctions relating to, for example, determining that a particular pilotstructure is specified for successive transmission time intervals(TTIs). Initially, the circuit/module for determining that a pilotstructure is specified for successive TTIs 1320 obtains information thatindicates that successive TTIs are similar (e.g., from the memory device1308, the communication interface 1302, or some other component of theapparatus 1300). For example, the information may indicate that thecommunication interface 1302 will be using the same beamformingconfiguration for successive TTIs. The circuit/module for determiningthat a pilot structure is specified for successive TTIs 1320 candetermine, based on the information, whether the pilot structure ofsuccessive TTIs will be the same. The circuit/module for determiningthat a pilot structure is specified for successive TTIs 1320 can thusdecide whether a receiving device can use a pilot from a prior TTI forchannel estimation associated with a later TTI. In addition, thecircuit/module for determining that a pilot structure is specified forsuccessive TTIs 1320 outputs an indication of the determination (e.g.,whether the same pilot structure is used for successive TTIs and/orwhether a pilot from a prior TTI can be used for channel estimation) toa component of the apparatus 1300 (e.g., the memory device 1308, thetransmitter 1314, the circuit/module for transmitting 1322, or someother component).

The circuit/module for transmitting 1322 may include circuitry and/orprogramming (e.g., code for transmitting 1332 stored on the storagemedium 1304) adapted to perform several functions relating to, forexample, transmitting an indication or other information. In someimplementations, the circuit/module for transmitting 1322 is configuredto transmit an indication that a pilot from a prior TTI can be used forchannel estimation. In some implementations, the circuit/module fortransmitting 1322 is configured to transmit an indication of a selectedpilot structure. In some implementations, the circuit/module fortransmitting 1322 is configured to transmit an indication of atraffic-to-pilot ratio. Initially, the circuit/module for transmitting1322 obtains data to be transmitted. For example, the circuit/module fortransmitting 1322 may obtain this data from a component of the apparatus(e.g., the memory device 1308, the circuit/module for determining that apilot structure is specified for successive TTIs 1320, thecircuit/module for selecting a pilot structure 1326, the circuit/modulefor determining a TPR 1328, or some other component). In someimplementations, the circuit/module for transmitting 1322 processes(e.g., encodes) the data to be transmitted. The circuit/module fortransmitting 1322 then causes the data to be transmitted. For example,the circuit/module for transmitting 1322 can pass the data to thetransmitter 1314 for subsequent radio frequency (RF) transmission. Insome implementations, the transmitter 1314 includes the circuit/modulefor transmitting 1322 and/or the code for transmitting 1332.

The circuit/module for identifying a PRB bundle 1324 may includecircuitry and/or programming (e.g., code for identifying a PRB bundle1334 stored on the storage medium 1304) adapted to perform severalfunctions relating to, for example, identifying a physical resourceblock (PRB) bundle that includes at least one PRB. Initially, thecircuit/module for identifying a PRB bundle 1324 obtains informationregarding resource requirements for future communications (e.g., basedon information stored in the memory device 1308, received from thecommunication interface 1302, or some other component). Thecircuit/module for identifying a PRB bundle 1324 then selects a PRBbundle (e.g., a wideband bundle) to be used for this communication basedon the PRB Bundling operations discussed above. The circuit/module foridentifying a PRB bundle 1324 then sends an indication of the identifiedPRB bundle to a component of the apparatus 1300 (e.g., the memory device1308, the circuit/module for selecting a pilot structure 1326, or someother component).

The circuit/module for selecting a pilot structure 1326 may includecircuitry and/or programming (e.g., code for selecting a pilot structure1336 stored on the storage medium 1304) adapted to perform severalfunctions relating to, for example, selecting a pilot structure based onan identified PRB bundle. Initially, the circuit/module for selecting apilot structure 1326 obtains information regarding a PRB bundle to beused for future communications (e.g., from the memory device 1308, thecircuit/module for identifying a PRB bundle 1324, or some othercomponent). The circuit/module for selecting a pilot structure 1326 thenselects a pilot structure to be used for this communication thataccommodates the PRB bundle. For example, the circuit/module forselecting a pilot structure 1326 may specify a pilot structure withpilots uniformly spread across a PRB bundle for wideband communication.The circuit/module for selecting a pilot structure 1326 then outputs anindication of the selected pilot structure to a component of theapparatus 1300 (e.g., the memory device 1308, the transmitter 1314, thecircuit/module for transmitting 1322, or some other component).

The circuit/module for determining a TPR 1328 may include circuitryand/or programming (e.g., a module for determining a TPR 1338 stored onthe storage medium 1304) adapted to perform several functions relatingto, for example, determining a traffic-to-pilot ratio (TPR) fordemodulation reference signals (DMRSs). Initially, the circuit/modulefor determining a TPR 1328 obtains information regarding channelconditions (e.g., from the memory device 1308, the communicationinterface 1302, or some other component). The circuit/module fordetermining a TPR 1328 then selects a TPR based on these channelconditions. For example, the circuit/module for determining a TPR 1328may select a TPR to meet a particular SNR target, error rate target, orsome other communication factor. In particular, the circuit/module fordetermining a TPR 1328 can optimize DMRS power for different MCSs,ranks, rates, and so on. The circuit/module for determining a TPR 1328then outputs an indication of the determined TPR to a component of theapparatus 1300 (e.g., the memory device 1308, the transmitter 1314, thecircuit/module for transmitting 1322, or some other component).

As mentioned above, programming stored by the storage medium 1304, whenexecuted by the processing circuit 1310, causes the processing circuit1310 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 1310, may cause the processing circuit 1310 toperform the various functions, steps, and/or processes described hereinwith respect to FIGS. 1-7 and 14-16 in various implementations. As shownin FIG. 13, the storage medium 1304 may include one or more of the codefor determining that a pilot structure is specified for successive TTIs1330, the code for transmitting 1332, the code for identifying a PRBbundle 1334, the code for selecting a pilot structure 1336, or the codefor determining a TPR 1338.

Example Processes

FIG. 14 illustrates a process 1400 for communication in accordance withsome aspects of the disclosure. In some implementations, the process1400 may be performed in addition to (e.g., in conjunction with) theprocess 900 of FIG. 9. The process 1400 may take place within aprocessing circuit (e.g., the processing circuit 1310 of FIG. 13), whichmay be located in a base station, an access terminal, or some othersuitable apparatus. In some implementations, the process 1400 representsoperations performed by the processing circuit 522 of FIG. 5. Of course,in various aspects within the scope of the disclosure, the process 1400may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 1402, an apparatus (e.g., a base station) determines that aparticular pilot structure is specified for successive transmission timeintervals (TTIs). That is, the apparatus determines that the pilotstructures for successive TTIs are the same. For example, an eNB maydetermine that the beamforming will (or has) not changed from one TTI tothe next and, consequently, the pilot structure will (or has) notchanged.

In some implementations, the circuit/module for determining that a pilotstructure is specified for successive TTIs 1320 of FIG. 13 performs theoperations of block 1402. In some implementations, the code fordetermining that a pilot structure is specified for successive TTIs 1330of FIG. 13 is executed to perform the operations of block 1402.

At block 1404, the apparatus transmits an indication that a pilot from aprior TTI can be used for channel estimation. In some aspects, theapparatus transmits this indication as a result of the determination ofblock 1402. In an example implementation, an eNB may transmit thisindication (e.g., by broadcasting the indication or by unicasting theindication to a UE). In some aspects, the pilot may be a demodulationreference signal (DMRS).

In some implementations, the circuit/module for transmitting 1322 ofFIG. 13 performs the operations of block 1404. In some implementations,the code for transmitting 1332 of FIG. 13 is executed to perform theoperations of block 1404.

FIG. 15 illustrates a process 1500 for communication in accordance withsome aspects of the disclosure. In some implementations, the process1500 may be performed in addition to (e.g., in conjunction with) theprocess 900 of FIG. 9. The process 1500 may take place within aprocessing circuit (e.g., the processing circuit 1310 of FIG. 13), whichmay be located in a base station, an access terminal, or some othersuitable apparatus. In some implementations, the process 1500 representsoperations performed by the processing circuit 622 of FIG. 6. Of course,in various aspects within the scope of the disclosure, the process 1500may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 1502, an apparatus (e.g., a base station) identifies a physicalresource block (PRB) bundle. The PRB bundle includes at least one PRB.

In some implementations, the circuit/module for identifying a PRB bundle1324 of FIG. 13 performs the operations of block 1502. In someimplementations, the code for identifying a PRB bundle 1334 of FIG. 13is executed to perform the operations of block 1502.

At block 1504, the apparatus selects a pilot structure based on theidentified PRB bundle. In some aspects, the selection of the pilotstructure includes selecting spacing for pilots based on a bandwidth ofthe PRB bundle. In some aspects, the pilot structure is for demodulationreference signals (DMRSs). In various scenarios, the selected pilotstructure may be the same as or different from the pilot structuredetermined at block 902 of FIG. 9 (e.g., the selected pilot structuremay be another pilot structure).

In some implementations, the circuit/module for selecting a pilotstructure 1326 of FIG. 13 performs the operations of block 1504. In someimplementations, the code for selecting a pilot structure 1336 of FIG.13 is executed to perform the operations of block 1504.

At block 1506, the apparatus transmits an indication of the selectedpilot structure (e.g., the selected other pilot structure). For example,the apparatus may broadcast the indication or unicast the indication toa UE. In some aspects, the indication may be a precoding matrixindicator (PMI). In some aspects, the indication indicates a differencebetween neighbor resource block (RB) PMIs.

In some implementations, the circuit/module for transmitting 1322 ofFIG. 13 performs the operations of block 1506. In some implementations,the code for transmitting 1332 of FIG. 13 is executed to perform theoperations of block 1506.

FIG. 16 illustrates a process 1600 for communication in accordance withsome aspects of the disclosure. In some implementations, the process1600 may be performed in addition to (e.g., in conjunction with) theprocess 900 of FIG. 9. The process 1600 may take place within aprocessing circuit (e.g., the processing circuit 1310 of FIG. 13), whichmay be located in a base station, an access terminal, or some othersuitable apparatus. In some implementations, the process 1600 representsoperations performed by the processing circuit 722 of FIG. 7. Of course,in various aspects within the scope of the disclosure, the process 1600may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 1602, an apparatus (e.g., a base station) determines atraffic-to-pilot ratio (TPR) for demodulation reference signals (DMRSs).In some aspects, the TPR is determined based on at least one of: amodulation and coding scheme (MCS), a rank, or a rate.

In some implementations, the circuit/module for determining a TPR 1328of FIG. 13 performs the operations of block 1602. In someimplementations, the code for determining a TPR 1338 of FIG. 13 isexecuted to perform the operations of block 1602.

At block 1604, the apparatus transmits an indication of the TPR. Forexample, the apparatus may broadcast the indication or unicast theindication to a UE.

In some implementations, the circuit/module for transmitting 1322 ofFIG. 13 performs the operations of block 1604. In some implementations,the code for transmitting 1332 of FIG. 13 is executed to perform theoperations of block 1604.

Example Apparatus

FIG. 17 illustrates a block diagram of an example hardwareimplementation of another apparatus 1700 configured to communicateaccording to one or more aspects of the disclosure. For example, theapparatus 1700 could embody or be implemented within a UE, a basestation (e.g., an eNB), or some other type of device that supportswireless communication. In various implementations, the apparatus 1700could embody or be implemented within an access terminal, an accesspoint, or some other type of device. In various implementations, theapparatus 1700 could embody or be implemented within a mobile phone, asmart phone, a tablet, a portable computer, a server, a personalcomputer, a sensor, an entertainment device, a vehicular component,medical devices, or any other electronic device having circuitry.

The apparatus 1700 includes a communication interface (e.g., at leastone transceiver) 1702, a storage medium 1704, a user interface 1706, amemory device 1708 (e.g., storing pilot-related information 1718), and aprocessing circuit (e.g., at least one processor) 1710. In variousimplementations, the user interface 1706 may include one or more of: akeypad, a display, a speaker, a microphone, a touchscreen display, ofsome other circuitry for receiving an input from or sending an output toa user. The communication interface 1702 may be coupled to one or moreantennas 1712, and may include a transmitter 1714 and a receiver 1716.In general, the components of FIG. 17 may be similar to correspondingcomponents of the apparatus 800 of FIG. 8.

According to one or more aspects of the disclosure, the processingcircuit 1710 may be adapted to perform any or all of the features,processes, functions, operations and/or routines for any or all of theapparatuses described herein. For example, the processing circuit 1710may be configured to perform any of the steps, functions, and/orprocesses described with respect to FIGS. 1-7 and 18-20. As used herein,the term “adapted” in relation to the processing circuit 1710 may referto the processing circuit 1710 being one or more of configured,employed, implemented, and/or programmed to perform a particularprocess, function, operation and/or routine according to variousfeatures described herein.

The processing circuit 1710 may be a specialized processor, such as anapplication specific integrated circuit (ASIC) that serves as a meansfor (e.g., structure for) carrying out any one of the operationsdescribed in conjunction with FIGS. 1-7 and 18-20. The processingcircuit 1710 serves as one example of a means for transmitting and/or ameans for receiving. In various implementations, the processing circuit1710 may incorporate the functionality of the processing circuit 524 ofFIG. 5, the processing circuit 624 of FIG. 6, or the processing circuit724 of FIG. 7.

According to at least one example of the apparatus 1700, the processingcircuit 1710 may include one or more of a circuit/module for receiving1720, a circuit/module for generating a channel estimate 1722, acircuit/module for selecting a transmit power 1724, or a circuit/modulefor transmitting 1726. In various implementations, the circuit/modulefor receiving 1720, the circuit/module for generating a channel estimate1722, the circuit/module for selecting a transmit power 1724, or thecircuit/module for transmitting 1726 may correspond, at least in part,to the processing circuit 524 of FIG. 5, the processing circuit 624 ofFIG. 6, or the processing circuit 724 of FIG. 7.

The circuit/module for receiving 1720 may include circuitry and/orprogramming (e.g., code for receiving 1728 stored on the storage medium1704) adapted to perform several functions relating to, for example,receiving information. In some implementations, the circuit/module forreceiving 1720 is configured to receive an indication that a pilot froma prior TTI can be used for channel estimation. In some implementations,the circuit/module for receiving 1720 is configured to receive TTIs. Insome implementations, the circuit/module for receiving 1720 isconfigured to receive an indication of a pilot structure selected basedon a PRB bundle. In some implementations, the circuit/module forreceiving 1720 is configured to receive a pilot according to a receivedindication of a pilot structure. In some implementations, thecircuit/module for receiving 1720 is configured to receive an indicationof a TPR for DMRSs. Initially, the circuit/module for receiving 1720obtains information. For example, the circuit/module for receiving 1720may obtain this information from a component of the apparatus (e.g., thememory device 1708, the receiver 1716, or some other component) ordirectly from a device (e.g., a base station, a user device, etc.) thattransmitted the information. In some implementations, the circuit/modulefor receiving 1720 identifies a location in the memory device 1708 orsome other component and invokes a read of that location to receive theinformation. In some implementations, the circuit/module for receiving1720 processes (e.g., decodes) the received information. Thecircuit/module for receiving 1720 then outputs the received informationto a component of the apparatus 1700 (e.g., the memory device 1708, thecircuit/module for generating a channel estimate 1722, thecircuit/module for selecting a transmit power 1724, or some othercomponent). In some implementations, the receiver 1716 includes thecircuit/module for receiving 1720 and/or the code for receiving 1728.

The circuit/module for generating a channel estimate 1722 may includecircuitry and/or programming (e.g., code for generating a channelestimate 1730 stored on the storage medium 1704) adapted to performseveral functions relating to, for example, generating a channelestimate based on received information. In some implementations, thecircuit/module for generating a channel estimate 1722 is configured togenerate a channel estimate for decoding data from a second TTI based,at least in part, on a pilot from a first TTI. In some implementations,the circuit/module for generating a channel estimate 1722 is configuredto generate a channel estimate based on a received pilot. Initially, thecircuit/module for generating a channel estimate 1722 obtains thereceived information (e.g., pilot information). For example, thecircuit/module for generating a channel estimate 1722 may obtain thisinformation from a component of the apparatus (e.g., the memory device1708, the receiver 1716, the circuit/module for receiving 1720, or someother component) or directly from a device (e.g., a base station, a userdevice, etc.) that transmits this information. The circuit/module forgenerating a channel estimate 1722 then estimates the channel over whichthe information was received based on information known about theoriginally transmitted information as well as transmitter and receiverparameters. Finally, the circuit/module for generating a channelestimate 1722 outputs the channel estimate (e.g., stores channelestimate information in the memory device 1708 or sends the informationto another component of the apparatus 1700). In some implementations,the communication interface 1702 includes the circuit/module forgenerating a channel estimate 1722 and/or the code for generating achannel estimate 1730.

The circuit/module for selecting a transmit power 1724 may includecircuitry and/or programming (e.g., code for selecting a transmit power1732 stored on the storage medium 1704) adapted to perform severalfunctions relating to, for example, selecting a transmit power based ona traffic-to-pilot ratio (TPR) for demodulation reference signals(DMRSs). Initially, the circuit/module for selecting a transmit power1724 obtains a TPR indication (e.g., from the memory device 1708, thereceiver 1716, the circuit/module for receiving 1720, or some othercomponent). The circuit/module for selecting a transmit power 1724 thenselects a transmit power based on the TPR and other power-relatedinformation (e.g., pilot power). Finally, the circuit/module forselecting a transmit power 1724 outputs an indication of the selectedtransmit power to a component of the apparatus 1700 (e.g., the memorydevice 1708, the transmitter 1714, the circuit/module for transmitting1726, or some other component).

The circuit/module for transmitting 1726 may include circuitry and/orprogramming (e.g., code for transmitting 1734 stored on the storagemedium 1704) adapted to perform several functions relating to, forexample, transmitting signals according to a selected transmit power.Initially, the circuit/module for transmitting 1726 obtains data to betransmitted and an indication of a selected transmit power. For example,the circuit/module for transmitting 1726 may obtain this data andindication from a component of the apparatus (e.g., the memory device1708, the circuit/module for selecting a transmit power 1732, or someother component). In some implementations, the circuit/module fortransmitting 1726 processes (e.g., encodes) the data to be transmitted.The circuit/module for transmitting 1726 then causes the data to betransmitted at the indicated transmit power. For example, thecircuit/module for transmitting 1726 can pass the data and indication oftransmit power to the transmitter 1714 for subsequent radio frequency(RF) transmission. In some implementations, the transmitter 1714includes the circuit/module for transmitting 1726 and/or the code fortransmitting 1734.

As mentioned above, programming stored by the storage medium 1704, whenexecuted by the processing circuit 1710, causes the processing circuit1710 to perform one or more of the various functions and/or processoperations described herein. For example, the programming, when executedby the processing circuit 1710, may cause the processing circuit 1710 toperform the various functions, steps, and/or processes described hereinwith respect to FIGS. 1-7 and 18-20 in various implementations. As shownin FIG. 17, the storage medium 1704 may include one or more of the codefor receiving 1728, the code for generating a channel estimate 1730, thecode for selecting a transmit power 1732, or the code for transmitting1734.

Example Processes

FIG. 18 illustrates a process 1800 for communication in accordance withsome aspects of the disclosure. In some implementations, the process1800 may be performed in addition to (e.g., in conjunction with) theprocess 1200 of FIG. 12. The process 1800 may take place within aprocessing circuit (e.g., the processing circuit 1710 of FIG. 17), whichmay be located in an access terminal, a base station, or some othersuitable apparatus. In some implementations, the process 1800 representsoperations performed by the processing circuit 524 of FIG. 5. Of course,in various aspects within the scope of the disclosure, the process 1800may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 1802, an apparatus (e.g., a UE) receives an indication that apilot from a prior transmission time interval (TTI) can be used forchannel estimation. For example, a UE can receive an indicationtransmitted by an eNB (e.g., as discussed above in conjunction withblock 1404 of FIG. 14).

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 1802. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 1802.

At block 1804, the apparatus receives during a first TTI. For example,the apparatus could receive a first TTI of a frame.

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 1804. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 1804.

At block 1806, the apparatus receives during a second TTI after thereceipt during the first TTI. For example, the apparatus could receive asecond TTI of a frame.

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 1806. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 1806.

At block 1808, the apparatus generates a channel estimate for decodingdata from a second TTI based on a pilot from the first TTI. In someaspects, the pilot may be a demodulation reference signal (DMRS).

In some implementations, the circuit/module for generating a channelestimate 1722 of FIG. 17 performs the operations of block 1808. In someimplementations, the code for generating a channel estimate 1730 of FIG.17 is executed to perform the operations of block 1808.

FIG. 19 illustrates a process 1900 for communication in accordance withsome aspects of the disclosure. In some implementations, the process1900 may be performed in addition to (e.g., in conjunction with) theprocess 1200 of FIG. 12. The process 1900 may take place within aprocessing circuit (e.g., the processing circuit 1710 of FIG. 17), whichmay be located in an access terminal, a base station, or some othersuitable apparatus. In some implementations, the process 1900 representsoperations performed by the processing circuit 624 of FIG. 6. Of course,in various aspects within the scope of the disclosure, the process 1900may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 1902, an apparatus (e.g., a UE) receives an indication. Forexample, a UE can receive an indication transmitted by an eNB (e.g., asdiscussed above in conjunction with block 1506 of FIG. 15). Theindication is of a pilot structure selected based on a physical resourceblock (PRB) bundle, the PRB bundle including at least one PRB. In someaspects, spacing for pilots defined by the pilot structure is based on abandwidth of the PRB bundle. In some aspects, the indication may be aprecoding matrix indicator (PMI). In some aspects, the indicationindicates a difference between neighbor resource block (RB) PMIs.

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 1902. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 1902.

At block 1904, the apparatus receives a pilot according to the indicatedpilot structure (e.g., from an eNB). In some aspects, the pilot may be ademodulation reference signal (DMRS).

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 1904. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 1904.

At block 1906, the apparatus generates a channel estimate. As discussedherein, this operation may be based on the received pilot.

In some implementations, the circuit/module for generating a channelestimate 1722 of FIG. 17 performs the operations of block 1906. In someimplementations, the code for generating a channel estimate 1730 of FIG.17 is executed to perform the operations of block 1906.

FIG. 20 illustrates a process 2000 for communication in accordance withsome aspects of the disclosure. In some implementations, the process2000 may be performed in addition to (e.g., in conjunction with) theprocess 1200 of FIG. 12. The process 2000 may take place within aprocessing circuit (e.g., the processing circuit 1710 of FIG. 17), whichmay be located in an access terminal, a base station, or some othersuitable apparatus. In some implementations, the process 2000 representsoperations performed by the processing circuit 724 of FIG. 7. Of course,in various aspects within the scope of the disclosure, the process 2000may be implemented by any suitable apparatus capable of supportingcommunication operations.

At block 2002, an apparatus (e.g., a UE) receives an indication of atraffic-to-pilot ratio (TPR) for demodulation reference signals (DMRSs).For example, a UE can receive an indication transmitted by an eNB (e.g.,as discussed above in conjunction with block 1604 of FIG. 16). In someaspects, the TPR is determined based on at least one of: a modulationand coding scheme (MCS), a rank, or a rate.

In some implementations, the circuit/module for receiving 1720 of FIG.17 performs the operations of block 2002. In some implementations, thecode for receiving 1728 of FIG. 17 is executed to perform the operationsof block 2002.

At block 2004, the apparatus selects a transmit power. As discussedherein, this selection is based on the TPR obtained at block 2002.

In some implementations, the circuit/module for selecting a transmitpower 1724 of FIG. 17 performs the operations of block 2004. In someimplementations, the code for selecting a transmit power 1732 of FIG. 17is executed to perform the operations of block 2004.

At block 2006, the apparatus transmits signals according to the selectedtransmit power. For example, the apparatus may transmit traffic at atransmit power level selected at block 2004.

In some implementations, the circuit/module for transmitting 1726 ofFIG. 17 performs the operations of block 2006. In some implementations,the code for transmitting 1734 of FIG. 17 is executed to perform theoperations of block 2006.

FIG. 21 is a schematic illustration of a wireless communication network2100 including multiple communication entities as it may appear in someaspects of the disclosure. As described herein, a scheduling entity oran entity being scheduled may reside in, or be a part of, a basestation, a smart phone, a small cell, or other entity. Subordinateentities or mesh nodes may reside in, or be a part of, a smart alarm, aremote sensor, a smart phone, a telephone, a smart meter, a personaldata assistant (PDA), a personal computer, a mesh node, and/or a tabletcomputer. Of course, the illustrated devices or components are merelyexamples, and any suitable node or device may appear within a wirelesscommunication network within the scope of the present disclosure.

Additional Aspects

One or more of the components, steps, features and/or functionsillustrated in the figures may be rearranged and/or combined into asingle component, step, feature or function or embodied in severalcomponents, steps, or functions. Additional elements, components, steps,and/or functions may also be added without departing from novel featuresdisclosed herein. The apparatus, devices, and/or components illustratedin the figures may be configured to perform one or more of the methods,features, or steps described herein. The novel algorithms describedherein may also be efficiently implemented in software and/or embeddedin hardware.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of example processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein. Additional elements,components, steps, and/or functions may also be added or not utilizedwithout departing from the disclosure.

While features of the disclosure may have been discussed relative tocertain implementations and figures, all implementations of thedisclosure can include one or more of the advantageous featuresdiscussed herein. In other words, while one or more implementations mayhave been discussed as having certain advantageous features, one or moreof such features may also be used in accordance with any of the variousimplementations discussed herein. In similar fashion, while exampleimplementations may have been discussed herein as device, system, ormethod implementations, it should be understood that such exampleimplementations can be implemented in various devices, systems, andmethods.

Also, it is noted that at least some implementations have been describedas a process that is depicted as a flowchart, a flow diagram, astructure diagram, or a block diagram. Although a flowchart may describethe operations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be re-arranged. A process is terminated when itsoperations are completed. In some aspects, a process may correspond to amethod, a function, a procedure, a subroutine, a subprogram, etc. When aprocess corresponds to a function, its termination corresponds to areturn of the function to the calling function or the main function. Oneor more of the various methods described herein may be partially orfully implemented by programming (e.g., instructions and/or data) thatmay be stored in a machine-readable, computer-readable, and/orprocessor-readable storage medium, and executed by one or moreprocessors, machines and/or devices.

Those of skill in the art would further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the implementations disclosed herein may beimplemented as hardware, software, firmware, middleware, microcode, orany combination thereof. To clearly illustrate this interchangeability,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system.

Within the disclosure, the word “exemplary” is used to mean “serving asan example, instance, or illustration.” Any implementation or aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects of the disclosure.Likewise, the term “aspects” does not require that all aspects of thedisclosure include the discussed feature, advantage or mode ofoperation. The term “coupled” is used herein to refer to the direct orindirect coupling between two objects. For example, if object Aphysically touches object B, and object B touches object C, then objectsA and C may still be considered coupled to one another—even if they donot directly physically touch each other. For instance, a first die maybe coupled to a second die in a package even though the first die isnever directly physically in contact with the second die. The terms“circuit” and “circuitry” are used broadly, and intended to include bothhardware implementations of electrical devices and conductors that, whenconnected and configured, enable the performance of the functionsdescribed in the disclosure, without limitation as to the type ofelectronic circuits, as well as software implementations of informationand instructions that, when executed by a processor, enable theperformance of the functions described in the disclosure.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining, and thelike. Also, “determining” may include receiving (e.g., receivinginformation), accessing (e.g., accessing data in a memory), and thelike. Also, “determining” may include resolving, selecting, choosing,establishing, and the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” or “at least one or more of” or “one or more of” alist of items refers to any combination of those items, including singlemembers. As an example, “at least one of: a, b, or c” is intended tocover: a; b; c; a and b; a and c; b and c; a, b and c; 2 a; 2 b; 2 c; 2a and b; a and 2 b, 2 a and 2 b; and so on. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for” or, in the case of a method claim, theelement is recited using the phrase “step for.”

Accordingly, the various features associate with the examples describedherein and shown in the accompanying drawings can be implemented indifferent examples and implementations without departing from the scopeof the disclosure. Therefore, although certain specific constructionsand arrangements have been described and shown in the accompanyingdrawings, such implementations are merely illustrative and notrestrictive of the scope of the disclosure, since various otheradditions and modifications to, and deletions from, the describedimplementations will be apparent to one of ordinary skill in the art.Thus, the scope of the disclosure is only determined by the literallanguage, and legal equivalents, of the claims which follow.

What is claimed is:
 1. An apparatus for communication, comprising: aprocessing circuit configured to identify a physical resource block(PRB) bundle that comprises at least one PRB, change a precoding matrixindicator (PMI) associated with the PRB bundle relative to the PMI of atleast one other PRB bundle and select a pilot structure for the PRBbundle in response to the change in the PMI, wherein the pilot structurecomprises pilots uniformly spread across the PRB bundle; and acommunication interface coupled to the processing circuit and configuredto transmit an indication of the pilot structure, wherein the indicationof the pilot structure comprises an indication of the change in the PMIof the PRB bundle relative to the PMI of the at least one other PRBbundle.
 2. The apparatus of claim 1, wherein the processing circuit isfurther configured to determine another pilot structure where pilotdensity differs over time within a transmission period, wherein thepilot density at a beginning portion of the transmission period ishigher than the pilot density at a later portion of the transmissionperiod.
 3. The apparatus of claim 2, wherein the pilot density isdifferent for different transmission time intervals (TTIs) within thetransmission period.
 4. The apparatus of claim 2, wherein the pilotdensity further differs with respect to frequency during thetransmission period.
 5. The apparatus of claim 2, wherein a transmitpower of pilots at a beginning portion of the transmission period ishigher than the transmit power of pilots at a later portion of thetransmission period.
 6. The apparatus of claim 2, wherein thetransmission period corresponds to a traffic burst.
 7. The apparatus ofclaim 2, wherein the processing circuit is further configured to: changea beamforming configuration; and determine the other pilot structure asa result of the change.
 8. The apparatus of claim 1, wherein the pilotstructure is for a demodulation reference signal (DMRS).
 9. Theapparatus of claim 1, wherein: the processing circuit is furtherconfigured to determine that a particular pilot structure is specifiedfor successive transmission time intervals (TTIs); and the communicationinterface is further configured to transmit an indication that a pilotfrom a prior TTI can be used for channel estimation, wherein theindication that a pilot from a prior TTI can be used for channelestimation is transmitted as a result of the determination that aparticular pilot structure is specified for successive TTIs.
 10. Theapparatus of claim 1, wherein, to select the pilot structure, theprocessing circuit is further configured to select spacing for pilotsbased on a bandwidth of the PRB bundle.
 11. The apparatus of claim 1,wherein the indication of the selected pilot structure comprises theprecoding matrix indicator (PMI).
 12. The apparatus of claim 1, whereinthe indication of the selected pilot structure indicates a differencebetween neighbor resource block (RB) PMIs.
 13. The apparatus of claim 1,wherein: the processing circuit is further configured to determine atraffic-to-pilot ratio (TPR) for demodulation reference signals (DMRSs);and the communication interface is further configured to transmit anindication of the TPR.
 14. The apparatus of claim 13, wherein the TPR isdetermined based on at least one or more of: a modulation and codingscheme (MCS), a rank, or a rate.
 15. The apparatus of claim 1, whereinthe processing circuit is further configured to perform an independentnetwork selection of the PMI for the PRB bundle.
 16. The apparatus ofclaim 1, wherein the communication interface is further configured totransmit the PMI, wherein the PMI indicates the pilot structure.
 17. Amethod of communication, comprising: identifying a physical resourceblock (PRB) bundle that comprises at least one PRB; changing a precodingmatrix indicator (PMI) associated with the PRB bundle relative to thePMI of at least one other PRB bundle; selecting a pilot structure forthe PRB bundle in response to the change in the PMI, wherein the pilotstructure comprises pilots uniformly spread across the PRB bundle; andtransmitting an indication of the pilot structure, wherein theindication of the pilot structure comprises an indication of the changein the PMI of the PRB bundle relative to the PMI of the at least oneother PRB bundle.
 18. The method of claim 17, further comprising:determining another pilot structure where pilot density differs overtime within a transmission period, wherein the pilot density at abeginning portion of the transmission period is higher than the pilotdensity at a later portion of the transmission period.
 19. The method ofclaim 18, wherein the pilot density is different for differenttransmission time intervals (TTIs) within the transmission period. 20.The method of claim 18, wherein the pilot density further differs withrespect to frequency or transmit power during the transmission period.21. The method of claim 18, further comprising: changing a beamformingconfiguration, wherein the other pilot structure is determined as aresult of the changing.
 22. The method of claim 17, wherein the pilotstructure is for a demodulation reference signal (DMRS).
 23. The methodof claim 17, further comprising: determining that a particular pilotstructure is specified for successive transmission time intervals(TTIs); and transmitting an indication that a pilot from a prior TTI canbe used for channel estimation, wherein the indication is transmitted asa result of the determination that a particular pilot structure isspecified for successive TTIs.
 24. The method of claim 17, furthercomprising: determining a traffic-to-pilot ratio (TPR) for demodulationreference signals (DMRSs); and transmitting an indication of the TPR.25. A non-transitory computer-readable medium storingcomputer-executable code, including code to: identify a physicalresource block (PRB) bundle that comprises at least one PRB; change aprecoding matrix indicator (PMI) associated with the PRB bundle relativeto the PMI of at least one other PRB bundle; select a pilot structurefor the PRB bundle in response to the change in the PMI, wherein thepilot structure comprises pilots uniformly spread across the PRB bundle;and transmit an indication of the pilot structure, wherein theindication of the pilot structure comprises an indication of the changein the PMI of the PRB bundle relative to the PMI of the at least oneother PRB bundle.
 26. The computer-readable medium of claim 25, furtherincluding code to: determine another pilot structure where pilot densitydiffers over time within a transmission period, wherein the pilotdensity at a beginning portion of the transmission period is higher thanthe pilot density at a later portion of the transmission period.
 27. Thecomputer-readable medium of claim 26, further including code to: changea beamforming configuration; and determine the other pilot structure asa result of the change.
 28. The computer-readable medium of claim 25,further including code to: determine that a particular pilot structureis specified for successive transmission time intervals (TTIs); andtransmit an indication that a pilot from a prior TTI can be used forchannel estimation, wherein the indication that a pilot from a prior TTIcan be used for channel estimation is transmitted as a result of thedetermination that a particular pilot structure is specified forsuccessive TTIs.
 29. The computer-readable medium of claim 25, furtherincluding code to: determine a traffic-to-pilot ratio (TPR) fordemodulation reference signals (DMRSs); and transmit an indication ofthe TPR.